Plastic lens material and process for preparing the same

ABSTRACT

Disclosed herein are a plastic lens material having both excellent optical and mechanical properties and having a low specific gravity, and a production process for producing the plastic lens material having excellent various properties and a low specific gravity. The plastic lens material comprises a copolymer obtained by radical-polymerizing a reaction product of a component [A] containing a polyhydric alcohol obtained by subjecting a dimer and/or a trimer of a higher unsaturated fatty acid having 11 to 22 carbon atoms with a component [B] containing an isocyanate compound having a radical-polymerizable unsaturated bond in its molecule together with a copolymerizable monomer [C].

TECHNICAL FIELD

The present invention relates to plastic lens materials and a productionprocess thereof, and more particularly to plastic lens materials fromwhich optical lenses having excellent optical properties and mechanicalproperties as well as a low specific gravity can be formed, and aproduction process thereof.

BACKGROUND ART

Plastic materials have begun being widely used as recent materials foroptical lenses from the viewpoints of lightweight property,processability, stability, dyeability, high-volume productioncapability, reducibility in cost, etc.

Among various properties required of materials for optical lenses, it isextremely important for them to have a low specific gravity. Morespecifically, if an optical lens formed of a material low in specificgravity is obtained, the use of such a lens permits reduction in theweight of a lens system, which occupies an important position in opticalinstruments, for example, microscopes, cameras and telescopes, andspectacle lenses.

Even in plastic lens materials, therefore, there is a tendency toattempt making their specific gravity further lower so as to stresspredominance over materials for inorganic glass lenses.

For example, a diethylene glycol bisallyl carbonate resin designated"CR-39" is known as a plastic material for spectacle lenses spreadingwidest at present. However, the specific gravity of this resin is ascomparatively high as 1.31 (in terms of a value measured at 20° C.; thesame shall apply to the following).

Besides, plastic lens materials containing halogen atoms or sulfur atomshave recently been known as materials for high-refractive index lenses.However, such plastic lens materials also have a specific gravity ascomparatively high as about 1.3 to 1.4.

Further, thermoplastic resins such as polystyrene (specific gravity:1.02), polymethyl methacrylate (specific gravity: 1.20) andpolycarbonate (specific gravity: 1.19) have been known as plastic lensmaterials having a comparatively low specific gravity. However, thesethermoplastic resins do not have sufficient optical properties requiredfrom the viewpoint of practical use.

On the other hand, copolymers having a crosslinked structure have beenintroduced as plastic lens materials excellent in various performancecharacteristics such as heat resistance, solvent resistance andmechanical strength. For example, "NIKON LIGHT DELUXE II" and the likehave been put to practical use as plastic lens materials having atriazine ring structure. The specific gravity of the plastic lensmaterial is as comparatively low as 1.17. However, this plastic lensmaterial cannot be yet said to be satisfactory for more reducing theweight of plastic lenses.

DISCLOSURE OF THE INVENTION

The present invention has been made on the basis of the foregoingcircumstances and has as its object the provision of a plastic lensmaterial having both excellent optical and mechanical properties andmoreover having a low specific gravity.

Another object of the present invention is to provide a process forproducing a plastic lens material having various excellent propertiesand a low specific gravity.

The present inventors have carried out an extensive investigation with aview toward achieving the above objects. As a result, it has been foundthat when a reaction product obtained by subjecting a polyhydricalcohol, which is obtained by subjecting a dimer and/or a trimer of aspecific higher unsaturated fatty acid to a reducing treatment, and anisocyanate compound having a radical-polymerizable unsaturated bond inits molecule to a urethanation reaction is radical-polymerized togetherwith a monomer copolymerizable with the reaction product, a copolymersuitable for use as a lens material having a low specific gravity,excellent transparency and a high refractive index is obtained. Thepresent invention has been led to completion on the basis of such afinding.

Namely, a plastic lens material according to the present inventioncomprises a copolymer obtained by polymerizing a monomer mixturecomprising 20 to 80 mass % of a reaction product (hereinafter may alsoreferred to as "radical-polymerizable urethane compound") obtained bysubjecting the following component [A] and the following component [B]to a urethanation reaction in proportions that a ratio (b/a) of thenumber (b) of moles of an isocyanate group contained in the component[B] to the number (a) of moles of hydroxyl groups contained in thecomponent [A] amounts to 0.5 to 3.0, and 80 to 20 mass % of a monomer(hereinafter may also referred to as "copolymerizable monomer [C]")copolymerizable with the reaction product.

Besides, a process according to the present invention for producing theplastic lens material comprises subjecting the following component [A]and the following component [B] to a urethanation reaction inproportions that a ratio (b/a) of the number (b) of moles of anisocyanate group contained in the component [B] to the number (a) ofmoles of hydroxyl groups contained in the component [A] amounts to 0.5to 3.0 to obtain a reaction product, mixing 20 to 80 mass % of thethus-obtained reaction product with 80 to 20 mass % of a monomercopolymerizable with the reaction product to prepare a monomer mixture,and radical-polymerizing the monomer mixture.

Component [A]:

a polyhydric alcohol-containing component composed of 60 to 100 mass %of at least one polyhydric alcohol selected from the following componentA¹ and the following component A², and 40 to 0 mass % of at least onecompound selected from the following component A³ and the followingcomponent A⁴ ;

(1) Component A¹ : at least one diol selected from a dimer diol obtainedby subjecting a dimer (hereinafter may also referred to as "dimer acid")of a higher unsaturated fatty acid having 11 to 22 carbon atoms to areducing treatment, and a dimer diol obtained by subjecting a dimer of alower alcohol ester (hereinafter may also referred to as "dimer aciddiester") of a higher unsaturated fatty acid having 11 to 22 carbonatoms to a reducing treatment;

(2) Component A² : at least one triol selected from a trimer triolobtained by subjecting a trimer (hereinafter may also referred to as"trimer acid") of a higher unsaturated fatty acid having 11 to 22 carbonatoms to a reducing treatment, and a trimer triol obtained by subjectinga trimer of a lower alcohol ester (hereinafter may also referred to as"trimer acid triester") of a higher unsaturated fatty acid having 11 to22 carbon atoms to a reducing treatment;

(3) Component A³ : an ether compound obtained by an intermoleculardehydration reaction of at least one polyhydric alcohol selected fromthe component A¹ and the component A² ;

(4) Component A⁴ : an ester compound obtained by reacting at least onepolyhydric alcohol selected from the component A¹ and the component A²with a carboxylic acid corresponding to the polyhydric alcohol; and

Component [B]:

an isocyanate compound-containing component composed of 50 to 100 mass %of an isocyanate compound B¹ having a radical-polymerizable unsaturatedbond in its molecule and 50 to 0 mass % of a polyisocyanate compound B²having no radical-polymerizable unsaturated bond in its molecule.

The present invention will hereinafter be described in detail.

<Component [A]>

The component [A] used for obtaining a plastic lens material accordingto the present invention is a component containing at least onepolyhydric alcohol selected from a group consisting of the component A¹(dimer diol) and the component A² (trimer triol) as an essentialcomponent and including at least one compound selected from a groupconsisting of the component A³ (ether compound) and the component A⁴(ester compound) as an optional component.

As higher unsaturated fatty acids used as raw materials for the dimeracid and dimer acid diester which are precursors of the dimer diols, andfor the trimer acid and trimer acid triester which are precursors of thetrimer triols, there may be used those having 1 to 4, preferably 1 or 2unsaturated bonds (double bonds) and 11 to 22, preferably 14 to 20, morepreferably 16 to 18 carbon atoms. If the number of carbon atoms of thehigher unsaturated fatty acid is less than 11, it is difficult to obtaina lens material having a low specific gravity. If the number of carbonatoms exceeds 22 on the other hand, it is difficult to obtain a lensmaterial having excellent mechanical properties because of reduction indensity of crosslinking, and the like.

Specific examples of such higher unsaturated fatty acids include oleicacid, elaidic acid, octadecenic acid, linolic acid, palmitoleic acid,myristoleic acid, linolenic acid, isooleic acid, eicosenoic acid,docosenic acid, branched chain octadecenic acid, branched chainhexadecenic acid and undecylenic acid. These higher unsaturated fattyacids may be used either singly or in any combination thereof.

As the lower alcohol ester of the higher unsaturated fatty acid(hereinafter may also referred to as "higher unsaturated fatty acidester" merely), there may be used an ester of any of the above-mentionedhigher unsaturated fatty acids with a lower aliphatic alcohol having 1to 6, preferably 1 to 4 carbon atoms. Examples thereof include methylesters, ethyl esters, propyl esters and butyl esters of the fatty acids.These higher unsaturated fatty acid esters may be used either singly orin any combination thereof.

As examples of reaction catalysts usable for dimerization ortrimerization of the higher unsaturated fatty acid and higherunsaturated fatty acid ester, may be mentioned liquid or solid Lewisacids and Br.o slashed.nsted acids. Specific examples thereof includevarious activated clays such as montmorillonite type activated clay andbentonite type activated clay, synthetic zeolites, silica-alumina, andsilica-magnesia. The use of the montmorillonite type activated clay isparticularly preferred. The amount of such a reaction catalyst to beadded is 1 to 20 mass %, preferably 2 to 8 mass %, based on the rawmaterial. The reaction temperature is 200 to 270° C., preferably 220 to250° C., while the reaction pressure is atmospheric pressure or apressure somewhat higher than atmospheric pressure, and specifically is1 to 10 atm. The reaction time is generally 5 to 7 hours though it maybe varied according to the amount of the catalyst and the reactiontemperature. This reaction tends to increase the viscosity of thereaction system as the reaction is allowed to progress. After completionof the reaction, the reaction catalyst is separated by filtration fromthe reaction mixture, and the reaction mixture is then subjected to, forexample, vacuum distillation, thereby distilling out an unreacted rawmaterial and by-products such as branched chain fatty acids. Thereafter,a dimer can be distilled out, and the distillation can be furthercontinued to distill out a trimer. When the higher unsaturated fattyacid is used as a raw material in the above reaction, a dimer acidhaving 2 carboxyl groups and a trimer acid having 3 carboxyl groups areprovided as the dimer and the trimer, respectively. On the other hand,when the higher unsaturated fatty acid ester is used as a raw material,a dimer acid diester having 2 ester groups and a trimer acid triesterhaving 3 ester groups are provided as the dimer and the trimer,respectively.

The thus-obtained dimers (dimer acid and dimer acid diester) aresubjected to a reducing treatment (hydrogenation), thereby obtainingdimer diols as the component A¹, while the trimers (trimer acid andtrimer acid triester) are subjected to a reducing treatment, therebyobtaining trimer triols as the component A².

As a process for subjecting the dimers and trimers to the reducingtreatment, there may be used any known chemical reduction process, forexample, a reduction process making use of a hydrogenating agent such aslithium aluminum hydride (LiAlH₄), lithium borohydride (LiBH₄) or ametallic sodium/alcohol system.

The reduction process will be described specifically. Lithium aluminumhydride is dispersed in a solvent such as diethyl ether or dioxane insuch a manner that the molar ratio of the lithium aluminum hydride is 2times the dimer component or 3 times the trimer component. The dimercomponent (dimer acid and/or dimer acid diester) and/or the trimercomponent (trimer acid and/or trimer acid triester) diluted with diethylether is gradually added dropwise to this dispersion over 1 to 2 hoursat 0° C. to room temperature, thereby conducting a reaction. Aftercompletion of the addition, the reaction mixture is stirred at roomtemperature for about 30 minutes, and water is then gradually addeddropwise in an amount about 4 times, in terms of molar ratio, of thelithium aluminum hydride added, thereby terminating the reaction. Dilutesulfuric acid is then added to the reaction mixture in an amount ofabout 10 mass % based on the reaction mixture to remove lithium andaluminum from the solvent layer. The solvent layer is washed with wateruntil waste water becomes neutral. The solvent in the solvent layer isthen removed, thereby obtaining polyhydric alcohol(s) (dimer diol and/ortrimer triol). Both polyhydric alcohols thus obtained are transparentand viscous liquids at room temperature.

As another process for subjecting the dimer component and trimercomponent to the reducing treatment, there may also be used a catalyticreduction process with hydrogen gas. When the hydrogenation is conductedby the catalytic reduction process, Raney nickel, platinum carryingnickel diatomaceous earth, copper-chromium, copper-zinc or the like isused as a catalyst. This catalyst is added to the dimer and/or trimercomponent in a proportion of 0.1 to 7 mass %. With respect to reactionconditions, the reaction temperature is 100 to 300° C., preferably 250to 280° C., the pressure of the hydrogen gas is atmospheric pressure to300 kg/cm², preferably 150 to 250 kg/cm², and the reaction time is 1 to15 hours, preferably 4 to 8 hours.

As examples of the polyhydric alcohols obtained in the above-describedmanner, may be mentioned dimer diols represented by the followinggeneral formulae (1) to (4), which are obtained by subjecting a dimer ofa higher unsaturated fatty acid having 18 carbon atoms to the reducingtreatment, and trimer triols obtained by reacting and bonding a dimerdiol represented by the general formula (1) or (3) with and to anunsaturated aliphatic alcohol represented by the following generalformula (5) or (6) at the respective unsaturated bond sites.

General formula (1): ##STR1## General formula (2): ##STR2## Generalformula (3): ##STR3## General formula (4): ##STR4## wherein m, n, p, q,m', n', p' and q' are independently 0 or an integer of 1 or greater,m+n+p+q equals 28, m+n equals m'+n'+1, and p+q equals p'+q'+3.

General formula (5):

    CH.sub.3 (CH.sub.2).sub.t CH═CHCH.sub.2 (CH.sub.2).sub.u CH.sub.2 OH

General formula (6):

    CH.sub.3 (CH.sub.2).sub.h (CH═CHCH.sub.2).sub.J CH═CH(CH.sub.2).sub.k CH.sub.2 OH

wherein t, u, h, j and k are independently 0 or an integer of 1 orgreater, t+u+5 equals 18, and h+3j+k+4 equals 18.

As examples of commercially available dimer diols obtained by subjectinga dimer of a higher unsaturated fatty acid to the reducing treatment,may be mentioned "Pespole HP-1000" (product of Toagosei ChemicalIndustry Co., Ltd.) and "Sobamole POL908" (product of Henkel HakusuiCorporation).

The component A³ as an optional component making up the component [A] isan ether compound obtained by an intermolecular dehydration reaction(condensation reaction at hydroxyl group sites) of at least onepolyhydric alcohol selected from the component A¹ (dimer diols) and thecomponent A² (trimer triols).

Such a component A³ can be obtained, for example, by subjecting thepolyhydric alcohol used as a raw material to a dehydration reaction at atemperature of 150 to 280° C. for 3 to 10 hours, preferably underreduced pressure, using an acid catalyst selected from p-toluenesulfonicacid, sulfuric acid, hydrogen fluoride, hydrogen trifluoride,methanesulfonic acid, activated clay, synthetic zeolites and the like ina proportion of 0.1 to 10 mass %, preferably 0.5 to 5 mass %, based onthe polyhydric alcohol.

The component A⁴ as an optional component making up the component [A] isan ester compound obtained by reacting at least one polyhydric alcoholselected from the component A¹ (dimer diols) and the component A²(trimer triols) with a carboxylic acid corresponding to the polyhydricalcohol.

The term the "carboxylic acid corresponding to the polyhydric alcohol"as used herein means a "dimer (monocarboxylic acid-monoalcohol)","trimer (dicarboxylic acid-monoalcohol)" or "trimer (monocarboxylicacid-diol)" obtained by partially hydrogenating a dimer acid, dimer aciddiester, trimer acid or trimer acid triester which is a precursor of thepolyhydric alcohol.

Such a component A⁴ can be obtained, for example, by adding, to thepolyhydric alcohol as a raw material, a carboxylic acid corresponding tothe polyhydric alcohol in such a manner that the hydroxyl groupscontained in the former polyhydric alcohol become an equimolar amount tothe carboxyl group(s) contained in the latter carboxylic acid to conductan esterification reaction at a temperature of 50 to 150° C. for 3 to 10hours using an acid catalyst selected from p-toluenesulfonic acid,sulfuric acid, hydrogen fluoride, hydrogen trifluoride, methanesulfonicacid and the like, or a base catalyst selected from sodium hydroxide,lithium hydroxide, metallic sodium and the like in a proportion of 0.1to 10 mass %, preferably 0.5 to 5 mass %, based on the polyhydricalcohol.

In the component [A] obtained by subjecting a precursor of thepolyhydric alcohol to the reducing treatment by the catalytic reductionprocess with hydrogen gas, the component A³ and/or the component A⁴ iscontained in a proportion of 1 to 15 mass % based on the whole component[A] together with the polyhydric alcohol (component A¹ and/or componentA²). This content can be enhanced to 15 to 40 mass % by removing waterand lower alcohol(s) secondarily produced during the reducing treatment.

The component A³ and component A⁴ are optional components making up thecomponent [A]. When the component A³ and/or the component A⁴ iscontained in the component [A], the falling ball strength (impactresistance) of a lens formed from the resulting lens material isimproved, and the reduction in specific gravity of the lens material canbe achieved with ease.

The total proportion of the component A³ and component A⁴ contained inthe component [A] is 0 to 40 mass %, preferably 5 to 30 mass %. If thisproportion exceeds 40 mass %, the viscosity of the component [A] and inits turn the monomer mixture becomes too high, so that the resultingcopolymer is deteriorated in flexibility.

<Component [B]>

The component [B] used for obtaining a plastic lens material accordingto the present invention is an isocyanate compound-containing componentcomposed of 50 to 100 mass % of an isocyanate compound B¹ (hereinafterreferred to as "component B¹ ") having a radical-polymerizableunsaturated bond in its molecule and 50 to 0 mass % of a polyisocyanatecompound B² (hereinafter referred to as "component B² ") having noradical-polymerizable unsaturated bond in its molecule.

As specific examples of the component B¹, may be mentioned methacryloylisocyanate, acryloyl isocyanate, methacryloylethyl isocyanate,acryloylethyl isocyanate, methacryloxyethyl isocyanate, acryloxyethylisocyanate, vinyldimethylbenzyl isocyanate andisopropenyldimethyl-benzyl isocyanate. These compounds may be usedeither singly or in any combination thereof.

Besides, a reaction product obtained by a urethanation reaction of apolyisocyanate compound having 2 or 3 isocyanate groups in its moleculewith a compound having at least one OH group and at least oneradical-polymerizable unsaturated bond in its molecule may also be usedas the component B¹.

As examples of the polyisocyanate compound used for obtaining theurethanation reaction product (component B¹), may be mentionedhexamethylene diisocyanate, octamethylene diisocyanate, isophoronediisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate,dicyclohexylmethane diisocyanate, tetramethylene diisocyanate, tolylenediisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalenediisocyanate, 3,3'-dimethyl-4,4'-bisphenylene diisocyanate, m-xylylenediisocyanate, a biuret reaction product of hexamethylene diisocyanate,isocyanate compounds of a trimer structure or their adduct reactionproducts with trimethylolpropane, trifunctional and tetrafunctionalpolyisocyanate compounds derived from isophorone diisocyanate, and2-isocyanatoethyl-2,6-diisocyanatoethyl hexanoate. These polyisocyanatecompounds may be used either singly or in any combination thereof.

As examples of the compound having at least one OH group and at leastone radical-polymerizable unsaturated bond in its molecule, which isused for obtaining the urethanation reaction product (component B¹), maybe mentioned acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate,3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate,2,3-dihydroxypropyl acrylate, 2,3-dihydroxy-propyl methacrylate,2-hydroxybutyl acrylate, 2-hydroxy-butyl methacrylate, 2-carboxyethylacrylate, 2-carboxy-ethyl methacrylate, vinylbenzoic acid and2-hydroxy-3-phenoxypropyl acrylate. These compounds may be used eithersingly or in any combination thereof.

The urethanation reaction for obtaining the urethanation reactionproduct as the component B¹ may be carried out in the presence of thecomponent [A] and other component of the component [B] than thecomponent B¹.

According to this process, "component B¹ -forming reaction" and"urethanation reaction of the component [B] containing the component B¹formed with the component [A]" are allowed to proceed side by side.Therefore, such a process is preferred because the production processcan be simplified.

The component B² as an optional component making up the component [B] isa polyisocyanate compound having no radical-polymerizable unsaturatedbond in its molecule. The incorporation of the component B² into thecomponent [B] permits controlling the molecular weight of the reactionproduct of the component [B] with the component [A] within a preferredrange (making the molecular weight higher).

As specific examples of such a component B², may be mentioned thepolyisocyanate compounds described above as those as may be used in thereaction for forming the component B¹ composed of the urethanationreaction product.

The proportion of the component B² contained in the component [B] is 0to 50 mass %. If this proportion exceeds 50 mass %, the viscosity of itsreaction product with the component [A] becomes too high, so that thehandling property of the reaction product is deteriorated, and moreoverits compatibility with the copolymerizable monomer [C] making up themonomer mixture is lowered. Therefore, the resulting copolymer (lensmaterial) is deteriorated in transparency, mechanical properties andheat resistance.

<Urethanation reaction of component [A] with component [B]>

The urethanation reaction of the component [A] with the component [B]can be conducted in an organic solvent inert to this reaction. Aftercompletion of the reaction, the solvent is removed, thereby obtaining aradical-polymerizable urethane compound. When the reaction system (themixture of the component [A] and the component [B]) is in the form of aliquid, the reaction may be conducted without using any organic solvent.The urethanation reaction may be conducted in the presence of thecopolymerizable monomer [C]. This process is preferred because theresultant reaction mixture can be used as the monomer mixture as it is.

The urethanation reaction of the component [A] with the component [B]may be conducted by heating the reaction system. However, a propercatalyst for the urethanation reaction is generally used from theviewpoint of shortening reaction time. As examples of such a catalyst,may be mentioned di-n-butyltin laurate, stannous octoate, dimethyltindichloride and stannic chloride.

Proportions of the component [A] and the component [B] used in theurethanation reaction must be such that assuming that the number ofmoles of hydroxyl groups contained in the component [A] and the numberof moles of an isocyanate group contained in the component [B] are a andb, respectively, a molar ratio (b/a) amounts to 0.5 to 3.0. If thismolar ratio is lower than 0.5, the resulting copolymer is too opaque tosatisfy optical properties required of lenses. If the ratio exceeds 3.0on the other hand, the resulting copolymer is deteriorated in weatherresistance and stability.

It is preferred that a monohydric aliphatic alcohol having at least 6carbon atoms should be contained in the reaction system. A reactionproduct obtained by using such an aliphatic alcohol in combination hasenhanced compatibility with the copolymerizable monomer [C] making upthe monomer mixture, whereby optical properties of the resultingcopolymer can be more enhanced. As specific examples of such amonohydric aliphatic alcohol, may be mentioned lauryl alcohol, myristylalcohol, palmityl alcohol and stearyl alcohol. These alcohols may beused either singly or in any combination thereof. The proportion of thealiphatic alcohol to be used is at most 40 mass % based on all thealcohol components from the viewpoint of retaining good mechanicalproperties of the resulting copolymer.

<Copolymerizable monomer [C]>

No particular limitation is imposed on the copolymerizable monomer [C]making up the monomer mixture together with the radical-polymerizableurethane compound, which is a reaction product of the component [A] withthe component [B], so far as it is a compound copolymerizable with thereaction product. Examples thereof may include compounds having at leastone acryloyl group, methacryloyl group, vinyl group or the like in theirmolecules.

As examples of the compounds having at least one acryloyl group ormethacryloyl group in their molecules, may be mentioned (meth)acrylateshaving an aliphatic alkyl group, such as methyl (meth)acrylate, ethyl(meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl(meth)acrylate, n-hexyl (meth)acrylate and isostearyl (meth)acrylate;(meth)acrylates having an aromatic or alicyclic group, such as phenyl(meth)acrylate, cyclohexyl (meth)acrylate, naphthyl (meth)acrylate and1,2,3-tribromophenyl (meth)acrylate; multifunctional (meth)-acrylatessuch as stearyl di(meth)acrylate, ethylene glycol di(meth)acrylate,polyethylene glycol poly(meth)-acrylate, propylene glycoldi(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycoldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanedioldi(meth)-acrylate, trimethylolpropane tri(meth)acrylate,tetramethylolmethane tri(meth)acrylate, tetramethylol-methanetetra(meth)acrylate, 2,2-bis[4-(meth)acryloxy-ethoxyphenyl]propane and2,2-bis[4-(meth)acryloxy-polyethoxyphenyl]propane; and ester compoundsobtained by reacting at least one polyhydric alcohol selected from thecomponent A¹ and the component A² with at least one acid selected fromacrylic acid and methacrylic acid. These compounds may be used eithersingly or in any combination thereof. In the above-mentioned compounds,the term "(meth)acrylate" means each of "acrylate" and "methacrylate".

The compounds having at least one vinyl group in its molecule arepreferably aromatic vinyl compounds having an aromatic ring because acopolymer having a high refractive index can be provided.

As examples of such an aromatic vinyl compound, may be mentionedstyrene, t-butylstyrene, α-methylstyrene, divinylbenzene,4-chlorostyrene, chloromethylstyrene, 4-hydroxymethylstyrene,ethylstyrene, o-methylstyrene and 4-methoxystyrene. These compounds maybe used either singly or in any combination thereof.

Of the above-mentioned compounds, t-butyl (meth)acrylate, isostearyl(meth)acrylate, stearyl di(meth)acrylate, styrene, t-butylstyrene,α-methylstyrene and divinylbenzene are preferred.

The compound used as the copolymerizable monomer [C] is not limited tothe above compounds. It is however preferable to select the kind of thecopolymerizable monomer [C] in such a manner that the resultingcopolymer has a specific gravity of 0.90 to 1.20, preferably 0.90 to1.10 and a refractive index of 1.45 to 1.60.

<Monomer mixture>

The monomer mixture subjected to a radical polymerization reaction inthe present invention is composed of the radical-polymerizable urethanecompound, which is a reaction product of the component [A] with thecomponent [B], and the copolymerizable monomer [C]. The proportions ofboth components in the monomer mixture are controlled in such a mannerthat a mass ratio of "the radical-polymerizable urethane compound to thecopolymerizable monomer [C]" is generally 20:80 to 80:20, preferably30:70 to 70:30. If the proportion of the radical-polymerizable urethanecompound is lower than 20 mass %, it is extremely difficult to obtain acopolymer having a low specific gravity (for example, a copolymer havinga specific gravity of 1.20 or lower). If this proportion exceeds 80 mass% on the other hand, the resulting copolymer fails to have goodmechanical properties.

The monomer mixture may also contain an antistatic agent, colorant,ultraviolet absorbent, heat stabilizer, antioxidant, filler and/or thelike as needed.

The monomer mixture as described above is polymerized, thereby obtaininga copolymer which constitutes the plastic lens material according to thepresent invention. The polymerization reaction mechanism may includeradical polymerization, ionic polymerization, photopolymerization andthe like. A process making use of a conventional radical polymerizationinitiator or photopolymerization initiator is preferred. For example,the radical polymerization may be conducted using a radicalpolymerization initiator capable of initiating a polymerization reactionat a temperature of 30 to 120° C. Besides, the photopolymerization maybe conducted at room temperature or so utilizing light from a highpressure mercury lamp or low pressure mercury lamp.

In the present invention, the radical-polymerizable urethane compoundmaking up the monomer mixture is a multifunctional monomer. Therefore, acrosslinked structure is introduced into the copolymer obtained from themonomer mixture. It is hence difficult to use this copolymer in amolding or forming process which involves dissolving or melting of thecopolymer. Accordingly, it is preferable to apply a cast polymerizationprocess, by which an intended form of a lens can be directly given, tothe monomer mixture as a polymerization process thereof.

A casting mold or frame in the form of a plate, lens, cylinder, squarepillar, cone, sphere or the like, which has been designed according tothe intended end and application of the resulting copolymer, is used asa vessel for the cast polymerization. The material of the vessel can beoptionally selected from inorganic glass, plastics, metals, etc. asnecessary for the end intended. The polymerization reaction can bepractically performed by charging the monomer mixture containing apolymerization initiator into the vessel for cast polymerization andthen heating it. However, it is also possible to conduct thepolymerization reaction by allowing the monomer mixture to react to acertain degree in advance in another reaction vessel and then pouringthe resultant prepolymer or syrup having an increased viscosity into thevessel for the cast polymerization to complete polymerization.

Besides, a forming process in which a copolymer in the form of a plateor block is formed by the cast polymerization, and a lens in a formintended is skived from the copolymer may also be adopted.

The molded or formed product (lens material) obtained in theabove-described manner may also be subjected to a surface-polishingtreatment, an antistatic treatment, a surface-coating treatment with asuitable organic or inorganic material, and/or the like as needed.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will hereinafter be described by the followingexamples. However, the present invention is not limited to and by theseexamples.

Incidentally, charged amounts upon polymerization in the followingexamples mean amounts of pure substances unless expressly noted. Alldesignations of "%" except for % used for light transmittance, and"part" or "parts" as will be used in the following examples mean "mass%" and "part or parts by mass", respectively.

The various performance characteristics of the lens materials obtainedin the following examples and comparative examples were evaluated in thefollowing manner:

(1) Transparency: evaluated by measuring the transmittance of visiblerays in accordance with JIS K 7105.

(2) Refractive index: evaluated by measuring a refractive index at 20°C. by an Abbe's refractometer.

(3) Specific gravity: measured in accordance with ASTM D 792.

(4) Impact resistance: tested whether a specimen (lens) is broken or notwhen a steel ball 16.33 g in weight is allowed to fall on the specimenfrom a height of 127 cm in accordance with the U.S. FDA standard.

PREPARATION EXAMPLE 1

One thousand grams of a mixture of higher unsaturated fatty acid methylesters, which contained 72% of methyl oleate, 18% of methyl linoleateand 10% of a higher saturated fatty acid methyl ester, were allowed toreact at 230° C. for 5 hours in the presence of 70 g of activated clayin a nitrogen atmosphere in a 2-liter autoclave. An unreacted higherunsaturated fatty acid methyl ester fraction and an isomerized higherunsaturated fatty acid methyl ester fraction were removed from theresultant reaction mixture by vacuum distillation (230° C./1 Torr), andthe residue was then subjected to molecular distillation (280° C./0.1Torr) to obtain about 450 g of dimer acid dimethyl esters.

Thereafter, 12 g (a proportion of 3% based on the dimer acid dimethylesters) of a copper-chromium catalyst were added to 400 g of thethus-obtained dimer acid dimethyl esters to hydrogenate the esters over10 hours by a catalytic reduction process while introducing hydrogen gasfor 10 minutes every 3 hours under conditions of a hydrogen gas pressureof 220 kg/cm² and a temperature of 270° C., thereby obtaining 340 g of amixture [hereinafter designated Component (A-1)] composed of 85% ofdimer diols (component A¹), 12% of ether compounds (component A³) formedby the intermolecular dehydration reaction of the dimer diols, and 3% ofester compounds (component A⁴) of the dimer diols with theircorresponding carboxylic acids.

PREPARATION EXAMPLE 2

Two hundred grams of Component (A-1) obtained in Preparation Example 1were subjected to molecular distillation (250° C./0.1 Torr), therebyobtaining 160 g of substantially pure dimer diols (component A¹ ;hydroxyl number: 199 KOH mg/g) [hereinafter designated Component (A-2)].

PREPARATION EXAMPLE 3

To 100 g of Component (A-2) obtained in Preparation Example 2 were added2 g of acid activated clay to conduct a dehydration reaction for 10hours at 200° C. in a nitrogen atmosphere. After completion of thereaction, the activated clay was removed by filtration from theresultant reaction mixture, and the residue was subjected to moleculardistillation, thereby removing unreacted dimer diols (component A¹) toobtain 75 g of ether compounds (component A³ ; hydroxyl number: 103 KOHmg/g) formed by the intermolecular dehydration reaction of the dimerdiols. The component A¹ and the component A³ were mixed in a proportionto give a molar ratio of 90:10 to obtain a mixture [hereinafterdesignated Component (A-3)].

PREPARATION EXAMPLE 4

One thousand grams of a mixture of higher unsaturated fatty acid esters,which contained 75% of methyl oleate, 15% of methyl linoleate and 9% ofmethyl stearate, were allowed to react at 230° C. for 5 hours in thepresence of 70 g of montmorillonite type activated clay in a nitrogenatmosphere in a 2-liter autoclave. After the catalyst was removed byfiltration from the reaction mixture, the reaction mixture was subjectedto molecular distillation to remove a monomer fraction distilled out ina temperature range of from 200 to 220° C. under a pressure of 0.3 to0.5 mmHg, thereby obtaining about 450 g of dimer acid dimethyl estersand about 150 g of trimer acid trimethyl esters. These dimer aciddimethyl esters and trimer acid trimethyl esters were mixed in amountsof 200 g and 50 g, respectively, to prepare a liquid mixture containingboth components at a mixing ratio of 80:20. This mixture in an amount of250 g was diluted with 350 ml of diethyl ether to prepare a diluteliquid mixture.

On the other hand, after purging the interior of a reactor equipped witha stirrer, condenser tube, thermometer, dropping funnel and nitrogen gasinlet tube with nitrogen gas, 32 g of lithium aluminum hydride werecharged into the reactor. While stirring the contents at roomtemperature in a nitrogen gas atmosphere, 1,200 ml of diethyl ether weregradually added into the reactor through the dropping funnel, therebyobtaining a dispersion of lithium aluminum hydride.

The dilute liquid mixture prepared above was added dropwise to thisdispersion over about 2 hours, thereby conducting a reaction. All thewhile, the temperature of the reaction system was kept at about 30° C.After completion of the addition, the reaction system was left to standfor 30 minutes, and 65 g of water were then gradually added dropwisethrough the dropping funnel. The reaction mixture thus obtained wasslowly transferred into a beaker containing 350 g of ice, and 250 g of a10% aqueous solution of sulfuric acid were then added to the beaker. Aproper amount of diethyl ether was further added to take an ether layerout of the beaker.

The ether layer thus recovered was then washed with water until wastewater became neutral. The solvent in the ether layer thus washed wasdistilled off under reduced pressure, thereby obtaining 210 g of amixture [hereinafter designated Component (A-4)] of 80% of dimer diols(component A¹) and 20% of trimer triols (component A²). This Component(A-4) was a transparent and viscous liquid and had a hydroxyl number of190 KOH mg/g.

PREPARATION EXAMPLE 5

A reactor equipped with a stirrer, nitrogen gas inlet tube, thermometer,condenser tube and water-measuring tube was charged with 21.0 g ofComponent (A-4) obtained in Preparation Example 4, 7.4 g of methacrylicacid, 0.015 g of p-methoxyphenol, 1.42 g of p-toluene-sulfonic acid and12 g of cyclohexane. The contents were heated to about 90° C. whileintroducing a small amount of air therein and stirring them. Whileremoving formed water outside the system of reaction through thewater-measuring tube in a state kept at this temperature, anesterification reaction was conducted for about 6 hours until the amountof the formed water amounted to 1.4 g.

After the resulting reaction product was then cooled, it was dissolvedin 18 g of diethyl ether. The resultant solution was neutralized with3.5 g of a 10% aqueous solution of sodium hydroxide to separate andremove a water layer.

After an ether layer was then washed with water until waste water becameneutral, 0.015 g of p-methoxy-phenol were added. The solvent was removedfrom the ether layer by vacuum distillation, thereby obtaining 23.7 g ofa mixture [hereinafter designated Component (C-1)] of the methacrylicesters of polyhydric alcohols. This Component (C-1) was analyzed byliquid chromatography. As a result, it was confirmed that a mass ratioof the dimer diol methacrylate to the trimer triol methacrylate was80:20.

EXAMPLE 1

(1) Synthesis of radical-polymerizable urethane compound:

A mixture composed of 18.8 parts of 2-methacryloxy-ethyl isocyanate(component B¹), 20 parts of styrene and 0.01 parts of di-n-butyltinlaurate (catalyst for urethanation reaction) was heated to 55° C. withstirring in accordance with its corresponding formulation shown in thefollowing Table 1. To this mixture, 31.2 parts of Component (A-2)obtained in Preparation Example 2 and 20 parts of styrene were graduallyadded dropwise over 60 minutes. In the resultant mixture, mixingproportions of the component B¹ and Component (A-2) were such that aratio (b/a) of the number (b) of moles of the isocyanate group containedin the component B¹ to the number (a) of moles of the hydroxyl groupscontained in Component (A-2) is 1.0. After completion of the addition,the mixture was kept at 55° C. for 60 minutes, thereby completing aurethanation reaction to prepare a mixture of a radical-polymerizableurethane compound and styrene.

(2) Radical polymerization (cast polymerization):

Ten parts of divinylbenzene and 1.0 part of lauroyl peroxide (radicalpolymerization initiator) were further added to and mixed into themixture of the radical-polymerizable urethane compound and styreneobtained in the step (1) to prepare a monomer mixture.

This monomer mixture was cast into a glass-made mold for a lens andsuccessively heated at different temperatures, i.e., 50° C. for 10hours, 60° C. for 8 hours, 80° C. for 3 hours and 100° C. for 2 hours toconduct polymerization, thereby producing a lens of -2.00 diopter.

(3) Performance evaluation:

This lens was excellent in transparency as demonstrated by atransmittance of visible rays of 91.5%, and had a refractive index ashigh as 1.517 and a specific gravity as extremely low as 1.044. Besides,its impact resistant test revealed that no breakage was observed, andthe lens hence had good mechanical properties.

EXAMPLES 2 to 5

Syntheses of radical-polymerizable urethane compounds and radicalpolymerization were conducted in the same manner as in Example 1 exceptthat the compositions of mixtures containing the component [B], and thekinds and amounts of the component [A] added dropwise to the mixtureswere changed in accordance with their corresponding formulations shownin Table 1, thereby producing lenses. The results of the performanceevaluation of the lenses thus obtained are shown collectively inTable 1. From the results shown in Table 1, it is understood that thelenses obtained by Examples 2 to 5 are all excellent in transparency,high in refractive index, low in specific gravity and also excellent inmechanical properties.

COMPARATIVE EXAMPLE 1

Synthesis of a urethane compound and polymerization were conducted inthe same manner as in Example 1 except that the composition of a mixturecontaining the component [B], and the kind and amount of Component (A-2)added dropwise to the mixture were changed in accordance with itscorresponding formulation shown in Table 1, thereby producing a lens.The thus-obtained lens was opaque and hence did not satisfy opticalproperties required of lenses. The lens was easily deformed by the forceof fingers and hence did not have sufficient mechanical properties. Thisreason is considered to be attributable to the fact that the urethanecompound formed from Component (A-2) and the component B² has noradical-polymerizable unsaturated bond, and so the compatibility of theurethane compound with styrene and divinylbenzene is deteriorated.

COMPARATIVE EXAMPLE 2

Synthesis of a radical-polymerizable urethane compound and radicalpolymerization were conducted in the same manner as in Example 2 exceptthat the amount of the component [B] used and the amount of thecomponent [A] added dropwise were changed in accordance with itscorresponding formulation shown in Table 1, thereby producing a lens.The thus-obtained lens was opaque and hence did not satisfy opticalproperties required of lenses. This reason is considered to beattributable to a molar ratio (b/a) as too low as 0.44.

                                      TABLE 1                                     __________________________________________________________________________                                    Comp.                                                                             Comp.                                       Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 1 Ex. 2                                   __________________________________________________________________________    I 2-Methacryloxy-                                                                         18.8                                                                              --  --  --  --  --  --                                           ethyl isocyanate                                                              (component B.sup.1)                                                           m-Isopropenyl- --  30.0 26.0 22.0 16.0 -- 11.0                                dimethylbenzyl                                                                isocyanate                                                                    (component B.sup.1)                                                           Methylenebis- -- -- --  --  --  15.4 --                                       phenyl isocyanate                                                             (component B.sup.2)                                                           Styrene 20.0 20.0 20.0 20.0 20.0 20.0 20.0                                    Di-n-butyltin 0.01 0.01 0.01 0.01 0.01 0.01 0.01                              laurate                                                                      II Component (A-2) 31.2 --  --  --  --  34.6 --                                [A.sup.1 = 100)                                                               Component (A-1) --  20.0 24.0 28.0 34.0 --  39.0                              [A.sup.1 :A.sup.3 :A.sup.4 = 85:12:3]                                         Styrene 20.0 20.0 20.0 20.0. 20.0 20.0 20.0                                Divinylbenzene                                                                            10.0                                                                              10.0                                                                              10.0                                                                              10.0                                                                              10.0                                                                              10.0                                                                              10.0                                        b/a [(NCO)/(OH)) 1.0 2.32 1.68 1.22 0.72 1.0 0.44                             Transmittance of 91.5 91.8 91.0 90.8 90.2 Opaque Opague                       visible rays (%)                                                              Refractive index 1.517 1.566 1.562 1.562 1.557 -- --                          Specific gravity 1.044 1.055 1.046 1.039 1.028 -- --                          Impact resistance None None None None None -- --                              (broken or not)                                                             __________________________________________________________________________     I: Mixture containing the component [B                                        II: Component added dropwise                                             

EXAMPLES 6 to 8

Syntheses of radical-polymerizable urethane compounds and radicalpolymerization were conducted in the same manner as in Example 1 exceptthat the compositions of mixtures containing the component [B], thekinds and amounts of the component [A] added dropwise, the amount ofstyrene added dropwise, and the amount of divinylbenzene used werechanged in accordance with their corresponding formulations shown inTable 2, thereby producing lenses. The results of the performanceevaluation of the lenses thus obtained are shown collectively in Table2. From the results shown in Table 2, it is understood that the lensesobtained by Examples 6 to 8 are all excellent in transparency, high inrefractive index, low in specific gravity and also excellent inmechanical properties.

                  TABLE 2                                                         ______________________________________                                                           Ex. 6 Ex. 7   Ex. 8                                        ______________________________________                                        I   m-Isopropenyldimethylbenzyl                                                                        8.6     --    5.5                                       isocyanate (component B.sup.1)                                                Methylenebisphenyl isocyanate 5.4 -- --                                       (component B.sup.2)                                                           Isocyanate compound having a --  23.0 --                                      radical-polymerizable unsaturated bond                                        *1 (component B.sup.1)                                                        Cyclic trimer of hexamethylene -- --  16.3                                    diisocyanate (component B.sup.2)                                              2-Hydroxybutyl methacrylate -- -- 4.3                                         Isostearyl alcohol -- -- 7.4                                                  Styrene 15.0 15.0 15.0                                                        Stearyl dimethacrylate 22.0 22.0 --                                           Isostearyl methacrylate --  --  12.0                                          Di-n-butyltin laurate 0.1 0.1 0.1                                            II Component (A-3) [A.sup.1 :A.sup.3 = 90:10] 26.0 17.0 16.5                   Styrene 16.0 16.0 16.0                                                     Divinylbenzene       7.0     7.0     7.0                                        b/a [(NCO)/(OH)] 1.0 1.0 1.0                                                  Transmittance of visible rays (%) 91.3 91.0 91.9                              Refractive index 1.545 1.549 1.537                                            Specific gravity 1.030 1.069 1.035                                            Impact resistance (broken or not) None None None                            ______________________________________                                         *1: A urethanation reaction product of 10.6 parts of mxylylene                diisocyanate with 12.4 parts of 2hydroxy-3-phenoxypropyl acrylate.            I: Mixture containing the component [B                                        II: Component added dropwise                                             

EXAMPLES 9 to 12

Syntheses of radical-polymerizable urethane compounds and radicalpolymerization were conducted in the same manner as in Example 1 exceptthat the compositions of mixtures containing the component [B], thekinds and amounts of the component [A] added dropwise, the amount ofstyrene added dropwise, and the amount of divinylbenzene used werechanged in accordance with their corresponding formulations shown inTable 3, thereby producing lenses. The results of the performanceevaluation of the lenses thus obtained are shown collectively in Table3. From the results shown in Table 3, it is understood that the lensesobtained by Examples 9 to 12 are all excellent in transparency, high inrefractive index, low in specific gravity and also excellent inmechanical properties.

EXAMPLE 13

Synthesis of a radical-polymerizable urethane compound and radicalpolymerization were conducted in the same manner as in Example 9 exceptthat 16.0 parts of t-butyl methacrylate were used in place of styrenemaking up the mixture containing the component [B], and 15.0 parts oft-butyl methacrylate were used in place of styrene making up thedropwise adding component in accordance with its correspondingformulation shown in Table 3, thereby producing a lens. The results ofthe performance evaluation of the lens thus obtained are showncollectively in Table 3. From the results shown in Table 3, it isunderstood that the lens obtained by Example 13 is excellent intransparency, high in refractive index, low in specific gravity and alsoexcellent in mechanical properties.

                                      TABLE 3                                     __________________________________________________________________________                        Ex. 9                                                                             Ex. 10                                                                            Ex. 11                                                                            Ex. 12                                                                            Ex. 13                                    __________________________________________________________________________    I m-Isopropenyldimethylbenzyl isocyanate                                                          16.0                                                                              20.0                                                                              24.0                                                                              16.0                                                                              16.0                                         (component B.sup.1)                                                           Styrene 16.0 14.0 12.0 10.0 --                                                t-Butyl methacrylate --  --  --  --  16.0                                     Stearyl dimethacrylate 22.0 16.0 10.0 -- 22.0                                 Component (C-1) [mixture of --  --  --  33.0 --                               methacrylic esters of polyhydric                                              alcohols]                                                                     Di-n-butyltin laurate 0.1 0.1 0.1 0.1 0.1                                    II Component (A-4) 24.0 30.0 36.0 24.0 24.0                                    [A.sup.1 :A.sup.2 = 80:20]                                                    Styrene 15.0 13.0 11.0 10.0 --                                                t-Butyl methacrylate --  --  --  --  15.0                                  Divinylbenzene      7.0 7.0 7.0 7.0 7.0                                         b/a [(NCO)/(OH)] 1.0 1.0 1.0 1.0 1.0                                          Transmittance of visible rays (%) 91.2 90.9 91.0 91.1 90.9                    Refractive index 1.544 1.544 1.545 1.536 1.517                                Specific gravity 1.021 1.024 1.028 1.013 1.009                                Inpact resistance (broken or not) None None None None None                  __________________________________________________________________________     I: Mixture containing the component [B                                        II: Component added dropwise                                             

EXAMPLE 14

Polymerization was conducted in the same manner as in Example 9 exceptthat 23.7 parts of a dimer diol (Pespole HP-1000; hydroxyl number: 196KOH mg/g) produced by Toagosei Chemical Industry Co., Ltd. were used asthe component [A], and the amount of the component B¹ used was changedfrom 16.0 parts to 16.3 parts [molar ratio (b/a)=1.0], thereby producinga lens. The performance of the lens thus obtained was as follows.Namely, the specific gravity was as low as 1.022, the refractive indexwas as high as 1.545, and its transparency was also excellent asdemonstrated by a transmittance of visible rays of 91.8%. Besides, itwas not broken in the impact resistant test, and its stiffness was alsosufficient.

EXAMPLE 15

A mixture composed of 21.5 parts of m-isopropenyl-dimethylbenzylisocyanate (component B¹), 20 parts of p-t-butylstyrene (copolymerizablemonomer [C]) and 0.01 parts of di-n-butyltin laurate (catalyst forurethanation reaction) was heated to 55° C. with stirring. To thismixture, 28.5 parts of a dimer diol (Sobamole POL908; hydroxyl number:205 KOH mg/g) produced by Henkel Hakusui Corporation) as a component [A]and 20 parts of p-t-butylstyrene (copolymerizable monomer [C]) weregradually added dropwise over 60 minutes. In the resultant mixture,mixing proportions of the component B¹ and the component [A] are suchthat a ratio (b/a) is 1.0. After completion of the addition, the mixturewas kept at 55° C. for 60 minutes, thereby completing a urethanationreaction to prepare a mixture of a radical-polymerizable urethanecompound and p-t-butylstyrene.

Polymerization was conducted in the same manner as in Example 1 exceptthat 10 parts of divinylbenzene (copolymerizable monomer [C]) and 1.0part of lauroyl peroxide (radical polymerization initiator) were furtheradded to and mixed into the thus-obtained mixture of theradical-polymerizable urethane compound and p-t-butyl-styrene to preparea monomer mixture, and this monomer mixture was used, thereby producinga lens. The thus-obtained lens was excellent in transparency asdemonstrated by a transmittance of visible rays of 91.5%, and had arefractive index as high as 1.543 and a specific gravity as extremelylow as 0.998. Besides, its impact resistant test revealed that nobreakage was observed, and the lens hence had good mechanicalproperties.

EFFECTS OF THE INVENTION

Since the plastic lens materials according to the present inventioncomprise a copolymer obtained by radical-polymerizing a reaction productof the component [A] containing the polyhydric alcohol derived from thespecific higher unsaturated fatty acid with the component [B] containingthe isocyanate compound having a radical-polymerizable unsaturated bondin its molecule, together with a monomer copolymerizable therewith, thelens materials are excellent in transparency and high in refractiveindex and have suitable optical properties required of optical lenses.In addition, they are excellent in mechanical properties such as impactresistance and stiffness and have a low specific gravity, so that theycan contribute sufficiently to reduction in the weight of lenses.

According to the production processes according to the presentinvention, plastic lens materials having excellent various properties asdescribed above can be produced with certainty.

What is claimed is:
 1. A plastic lens material comprising a copolymerobtained by polymerizing a monomer mixture comprising:20 to 80 mass % ofa reaction product obtained by subjecting the following component [A]and the following component [B] to a urethanation reaction inproportions that a ratio (b/a) of the number (b) of moles of anisocyanate group contained in the component [B] to the number (a) ofmoles of hydroxyl groups contained in the component [A] amounts to 0.5to 3.0; and 80 to 20 mass % of a monomer copolymerizable with thereaction product;Component [A]:a polyhydric alcohol-containing componentcomposed of 60 to 100 mass % of at least one polyhydric alcohol selectedfrom the following component A¹ and the following component A², and 40to 0 mass % of at least one compound selected from the followingcomponent A³ and the following component A⁴ ; [Component A¹ ]: at leastone diol selected from a dimer diol obtained by subjecting a dimer of ahigher unsaturated fatty acid having 11 to 22 carbon atoms to a reducingtreatment, and a dimer diol obtained by subjecting a dimer of a loweralcohol ester of a higher unsaturated fatty acid having 11 to 22 carbonatoms to a reducing treatment; [Component A² ]: at least one triolselected from a trimer triol obtained by subjecting a trimer of a higherunsaturated fatty acid having 11 to 22 carbon atoms to a reducingtreatment, and a trimer triol obtained by subjecting a trimer of a loweralcohol ester of a higher unsaturated fatty acid having 11 to 22 carbonatoms to a reducing treatment; [Component A³ ]: an ether compoundobtained by an intermolecular dehydration reaction of at least onepolyhydric alcohol selected from the component A¹ and the component A² ;[Component A⁴ ]: an ester compound obtained by reacting at least onepolyhydric alcohol selected from the component A¹ and the component A²with a carboxylic acid corresponding to the polyhydric alcohol; andComponent [B]:an isocyanate compound-containing component composed of 50to 100 mass % of an isocyanate compound B¹ having aradical-polymerizable unsaturated bond in its molecule and 50 to 0 mass% of a polyisocyanate compound B² having no radical-polymerizableunsaturated bond in its molecule.
 2. The plastic lens material accordingto claim 1, which comprises a copolymer obtained by polymerizing amonomer mixture comprising 30 to 70 mass % of the reaction productobtained by subjecting the component [A] and the component [B] to theurethanation reaction, and 70 to 30 mass % of the monomercopolymerizable with the reaction product.
 3. The plastic lens materialaccording to claim 1, wherein the component A¹ is at least one diolselected from a dimer diol obtained by subjecting a dimer of a higherunsaturated fatty acid having 14 to 20 carbon atoms to a reducingtreatment, and a dimer diol obtained by subjecting a dimer of a loweralcohol ester of a higher unsaturated fatty acid having 14 to 20 carbonatoms to a reducing treatment.
 4. The plastic lens material according toclaim 1, wherein the component A¹ is at least one diol selected from adimer diol obtained by subjecting a dimer of a higher unsaturated fattyacid having 16 to 18 carbon atoms to a reducing treatment, and a dimerdiol obtained by subjecting a dimer of a lower alcohol ester of a higherunsaturated fatty acid having 16 to 18 carbon atoms to a reducingtreatment.
 5. The plastic lens material according to claim 1, whereinthe component A² is at least one triol selected from a trimer triolobtained by subjecting a trimer of a higher unsaturated fatty acidhaving 14 to 20 carbon atoms to a reducing treatment, and a trimer triolobtained by subjecting a trimer of a lower alcohol ester of a higherunsaturated fatty acid having 14 to 20 carbon atoms to a reducingtreatment.
 6. The plastic lens material according to claim 1, whereinthe component A² is at least one triol selected from a trimer triolobtained by subjecting a trimer of a higher unsaturated fatty acidhaving 16 to 18 carbon atoms to a reducing treatment, and a trimer triolobtained by subjecting a trimer of a lower alcohol ester of a higherunsaturated fatty acid having 16 to 18 carbon atoms to a reducingtreatment.
 7. The plastic lens material according to claim 1, whereinthe total proportion of the component A³ and the component A⁴ containedin the component [A] is 5 to 30 mass %.
 8. The plastic lens materialaccording to claim 1, wherein the copolymerizable monomer is a compoundhaving at least one selected from an acryloyl group, methacryloyl groupand vinyl group in its molecule.
 9. The plastic lens material accordingto claim 1, wherein the copolymerizable monomer is at least one selectedfrom t-butyl (meth)acrylate, isostearyl (meth)acrylate, stearyldi(meth)acrylate, styrene, t-butylstyrene, α-methylstyrene anddivinylbenzene.
 10. A process for producing a plastic lens material,comprising:subjecting the following component [A] and the followingcomponent [B] to a urethanation reaction in proportions that a ratio(b/a) of the number (b) of moles of an isocyanate group contained in thecomponent [B] to the number (a) of moles of hydroxyl groups contained inthe component [A] amounts to 0.5 to 3.0 to obtain a reaction product;mixing 20 to 80 mass % of the thus-obtained reaction product with 80 to20 mass % of a monomer copolymerizable with the reaction product toprepare a monomer mixture; and radical-polymerizing the monomermixture;Component [A]:a polyhydric alcohol-containing component composedof 60 to 100 mass % of at least one polyhydric alcohol selected from thefollowing component A¹ and the following component A², and 40 to 0 mass% of at least one compound selected from the following component A³ andthe following component A⁴, [Component A¹ ]: at least one diol selectedfrom a dimer diol obtained by subjecting a dimer of a higher unsaturatedfatty acid having 11 to 22 carbon atoms to a reducing treatment, and adimer diol obtained by subjecting a dimer of a lower alcohol ester of ahigher unsaturated fatty acid having 11 to 22 carbon atoms to a reducingtreatment; [Component A² ]: at least one triol selected from a trimertriol obtained by subjecting a trimer of a higher unsaturated fatty acidhaving 11 to 22 carbon atoms to a reducing treatment, and a trimer triolobtained by subjecting a trimer of a lower alcohol ester of a higherunsaturated fatty acid having 11 to 22 carbon atoms to a reducingtreatment; [Component A³ ]: an ether compound obtained by anintermolecular dehydration reaction of at least one polyhydric alcoholselected from the component A¹ and the component A² ; [Component A⁴ ]:an ester compound obtained by reacting at least one polyhydric alcoholselected from the component A¹ and the component A² with a carboxylicacid corresponding to the polyhydric alcohol; and Component [B]:anisocyanate compound-containing component composed of 50 to 100 mass % ofan isocyanate compound B¹ having a radical-polymerizable unsaturatedbond in its molecule and 50 to 0 mass % of a polyisocyanate compound B²having no radical-polymerizable unsaturated bond in its molecule. 11.The production process of the plastic lens material according to claim10, which comprises mixing 30 to 70 mass % of the reaction productobtained by subjecting the component [A] and the component [B] to theurethanation reaction with 70 to 30 mass % of the monomercopolymerizable with the reaction product to prepare a monomer mixture,and radical-polymerizing the monomer mixture.
 12. The production processof the plastic lens material according to claim 10, wherein thecomponent A¹ is at least one diol selected from a dimer diol obtained bysubjecting a dimer of a higher unsaturated fatty acid having 14 to 20carbon atoms to a reducing treatment, and a dimer diol obtained bysubjecting a dimer of a lower alcohol ester of a higher unsaturatedfatty acid having 14 to 20 carbon atoms to a reducing treatment.
 13. Theproduction process of the plastic lens material according to claim 10,wherein the component A¹ is at least one diol selected from a dimer diolobtained by subjecting a dimer of a higher unsaturated fatty acid having16 to 18 carbon atoms to a reducing treatment, and a dimer diol obtainedby subjecting a dimer of a lower alcohol ester of a higher unsaturatedfatty acid having 16 to 18 carbon atoms to a reducing treatment.
 14. Theproduction process of the plastic lens material according to claim 10,wherein the component A² is at least one triol selected from a trimertriol obtained by subjecting a trimer of a higher unsaturated fatty acidhaving 14 to 20 carbon atoms to a reducing treatment, and a trimer triolobtained by subjecting a trimer of a lower alcohol ester of a higherunsaturated fatty acid having 14 to 20 carbon atoms to a reducingtreatment.
 15. The production process of the plastic lens materialaccording to claim 10, wherein the component A² is at least one triolselected from a trimer triol obtained by subjecting a trimer of a higherunsaturated fatty acid having 16 to 18 carbon atoms to a reducingtreatment, and a trimer triol obtained by subjecting a trimer of a loweralcohol ester of a higher unsaturated fatty acid having 16 to 18 carbonatoms to a reducing treatment.
 16. The production process of the plasticlens material according to claim 10, wherein the total proportion of thecomponent A³ and the component A⁴ contained in the component [A] is 5 to30 mass %.
 17. The production process of the plastic lens materialaccording to claim 10, wherein the copolymerizable monomer is a compoundhaving at least one selected from an acryloyl group, methacryloyl groupand vinyl group in its molecule.
 18. The production process of theplastic lens material according to claim 10, wherein the copolymerizablemonomer is at least one selected from t-butyl (meth)acrylate, isostearyl(meth)acrylate, stearyl di(meth)acrylate, styrene, t-butylstyrene,α-methylstyrene and divinylbenzene.
 19. The production process of theplastic lens material according to claim 10, which comprises subjectingthe component [A] and the component [B] to the urethanation reaction inthe presence of the copolymerizable monomer.
 20. The production processof the plastic lens material according to claim 10, wherein a monohydricaliphatic alcohol having at least 6 carbon atoms is contained in thereaction system of the urethanation reaction.